Abstract: It is more difficult to protect the patent of chemical analysis methods, than it is for actual products, as they are akin to a process patent. Since chemical analysis methods are generally developed in the workplace, it is difficult to establish identity. Therefore, the identification of infringement to chemical analysis methods patents is also difficult. In this case, the writing quality of claims will directly affect whether the patentee's benefit can be protected. In this paper, several typical problems in the claims of chemical analysis methods patent will be illustrated. Also, all the principles and doctrines of autogenesis for the identification of infringement will be highlighted. According to the many requirements of volume, weight, acidity, alkaline, heating, cooling, operation procedure and formula, we demonstrate both independent claims and dependent claims for a real case step by step, pointing out the requirements of embodiment with a large number of parameters, and indicating the situation when the amendments of requirements easily go beyond the scope of the claim.